Rotary hydraulic coupling



2 Sheets-Sheet 2 Filed may 22. 1951 v fill/dz Patented Sept. 21, 1954 uEn: PAT ENF @FFIQE mesa-15's" ROTARY HYDRAULIC COUPLING: VCliai'ls'TerrsWeymann, Paris, Fiance Application May 22; 1951;SerialNow227563 Claims 1mor1tv, appiiiiation France May 25, 1950 The-presentinvention relates to tlie Fottingeitype of 7 hydraulic power transmitteror fluidcon pling in which driving"and diiven'meni-bers are' catchprovided with anannular series of vanes; blades-or passages; and the'two'members ai'e -so designed and so juxtap'osed that theimpellingliquid whiletravelling" the operating circuit defined b'y saidblads or passages *eflects thero tation' 01 the driven member in:response to the rotation of the driving member;

Couplings of= this ityperoffer manwadvantages: as a: very "high deg re'eof I startin gti'smooth ness; this? operation. being effected; withoutany special p'edal, undQ'ai-Lthe Imerei controls of itheinor malacceleratlozt oi'wthe engine, .aLhigh'er degree: or saiety againstcutting out'ioflthe'engineysilent operationgzab'sence: of wear and'sown. These couplings; h0W8V81,'. have" the drawback in that it is:diflicult to oldtain' at the same time the de shied disengagem'ent'ofthencotpli-ng; as'stheren gine isth'rottled down; and'the'total powertrans mission with aminimnm slippag'e betwe'emthe: driving. and-drivenshafts as the-engine is spe'eded': upa i 1 t-yis an objectwf theinventionto provide" a hydraulic couplingvofthe type describedwhieh iscapable of ensuring both a:- complete dec1utching;- as theengineisth'rottled down and' a substan tialliz ifistantan'eous reolutc'liing,as the engine is speededup'agam;

Acdordingto the" presentiiiveiitioii. there: is"

provideda hydiaulic coupling comprising a pump tion"; when thespeedf'ofthe"driving'shaftreacfies a predeterminedvalue,theoutlet port"of ports are" closed and the" above mentioned feeding rne'ans" ensure aproper filling of the device? Wheelr'otatin'gr' with adrlviiig'shait,turbine wheel secured= to a driven shaft-l casing" fiired to saidpumwwh'el foi rotation therewith} and enclosing sald' turbine: wheelmeans di'iven by" said driving shafif fon' continuously suppljiingHquid-iuuder ressurerinto saidicasi lea'stf one liquidaoutletvport inthe'iperiplietieall wazil of -s'aid' casmg;.overflow means:forvcondueting said iq uidIzfi-omi the :interior or said' -casihigl tosaid out let: pormsaids overflow? means determining tne" highest levelor a? liquid volumeconstantly re tamedin said casingwheri saiddiitlet-fioh 5- open, and icentriiugallt *operated vaivemeans as mintedwitlilsaid 'outlet 'port for preventimg liwutdoverflowingt said levelfrom? discha ging through said? outletport when said calsingi r0tdtesabove avpredetemninectspeed;

n The :liquid: may! be supplied fromia sumwcoiistitutedby the bottom octthaelhousing o't th'e 'de= viceiath'e 1 liquidi supplyingi meansbeingadapted tb recycl'elcontinuouslyithe llqiiid evacil'ated ffbfii thecasing into saidvsu'inpz nWiththmarrangementqiaeordingfitdthe inven-Wl'ienthe engine slowsdowri under agiven value;- the strength of thespring tending to openeaoh valvebecomes higher than the-combined actionof the-centrifugal force -and liquid pressure act'- ing inthe oppositedirection, and* causes the openingof the 'outlet port" controlled bysaid valve; so that the" above mentioned predetermined'amountof theliquid is expelled under-the action of centrifugal force through L saidoutlet port thus" reducing the} maximum torque which canbeti'ansmittedmy th'ecoupling;

In a preferred embodiment of the invention; the overflow means forconducting liquid; tothe outlet-port} is constitn-tdby a passageextendmy ream-11y ffom =the interior of the casing w an outlet port inthe periphery of' thecasingg'said part being controlled bysaid valve.

This arrangement provides three advantages viz. the valve is located ata point where itsiop eratiiig condition's are optimum, the evacuationofthe-liquid; sinoe it takes placethroug ai radi'al passage, is rapidlyeifectedmy oenti iiuigal fi 'jtoe; and the casingl'cannot be emptiedbelow a certain 1eve1 determined byii'the :position of the 'n"-= ner endof saidrrpassage 'soithat thez-re-fillin gr-of the casingg when theengine ris speeded up iagain, takespla'ce rapidly; which ensuresaisubstaritially instantarieou's' reclutching;

For" each outlet 'ort there maybe provided a; secondary: 'outviardlywpenin g valve mounted iri series-'6 with the above: mentionedvalve means (hereafter also called the primary-valve) either upstream ordownstream with respecmo the same; said Secol idal-"y' valve being Yadapted 110- be brought by slight c'entrifugal force into its open-- ingposition; while it is' u'tge'd into itsclosing position an opposingspring sii-ita'bly" Callbrated; so than said secondary" valve remainsclosed under"- a relatiwiely' slow predetermined speed -lower thantheclosing and opening speeds" of the niain valve."

With this arrangement} the secondiiy valveis awaysepned before theprimary valveis' cldse'df When" due to deceleration; the primary valve"opens-, the secondary valve' remains also opened" closes At "and-belowsaidlast mentioned speed an'd even' when the -engine is completelystopped;

said scondary 'valire always remains closed,

Additional feeding means actuated from the 3 driven shaft may beprovided for feeding the casing when the driven shaft is rotating andthe driving shaft is at rest.

Bleed means constituted by outlets may be provided in the pump wheel inthe vicinity of the casing axis and controlled by spring loadednonreturn valves opening outwardly under a predetermined pressure, whilepreventing the liquid from escaping at pressures below said pressure.

Since the casing can never be emptied, any torque generated by thedriven shaft will be transmitted to the driving shaft thereby startingor assisting in starting the engine. Said engine then transmits to thedriving shaft a speed sufficient to cause the opening of the secondaryvalve,

thus re-establishing the normal running conditions.

The invention is illustrated by way of example in the accompanyingdrawings in which:

Fig. 1 is an axial section of a hydraulic coupling according to oneembodiment of the invention.

Fig. 2 is a section along line 2-2 of Fig. 1.

Fig. 3 is a view similar to Fig. lof another embodiment comprising twovalves for each outlet, the secondary valve being located downstream ofthe primary valve.

Fig. 4 is a detail view of the primary and secondary valves in theposition corresponding to a speed comprised within the secondary valveopening speed and the primary valve closing speed.

Fig. 5 is a part view of said valves in the normal running condition, i.e. at a speed higher than the closing speed of the primary valve.

Fig. 6 shows an alternative arrangement in which the valves arecircumferentially spaced in order to provide a reduction of the radialthickness of the casing.

Fig. 7 shows an alternative embodiment in which the bleed means areconstituted by spring loaded ball valves.

Fig. 8 is a modification of Fig. 3 in which the secondary valve islocated upstream of the primary valve.

Fig. 9 shows an alternative construction of the embodiment of Fig. 6 inwhich the valves are circumferentiallyspaced.

Referring to the drawings, there is shown at I, the housing of ahydraulic coupling, at 2 thedriving shaft and at 3 the driven shaft.

On driving shaft 2 is fixed for.rotation with said shaft a casing 4carrying a driving centrifugal pump 5 which projects, when shaft 2rotates, a strong oil stream onto the blades of a receiving turbine 6fixed on the driven shaft 3 for rotation therewith. In the exampleshown, there are provided, in the outer periphery of easing 4, a numberof liquid outlet ports 1 controlled by valves 8 adapted to be brought bycentrifugal force into their closing position, a spring 9 urging saidvalves towards the opening position. The outlet ports I communicate withthe working chamber of the coupling through overflow means which, in theexample shown, are constituted by a radial duct lb opening into saidworking chamber at a point thereof lying nearer to the axis of thecoupling than the point of said chamber remotest from said axis, so asto determine a highest level, indicated by line 1a, ofconstantlyretained liquid, as hereinafter more fully explained. There isshown at Ill a rotary pump, the

. rotor of which is rotated from shaft 2, said pump sucking through apipe H oil contained in the sump 12. The oil discharged from said pumpflows, as indicated by arrows in Fig. 1, through ducts I5 provided inthe surface of shaft 3 and .4 passages l4 provided in the hub of theturbine wheel -6, and is directed towards the working space of thecoupling comprised between the vanes of members 5 and 6. A portion ofsaid oil is by-passed through bearings l3, which improves theirlubrication.

It will be understood that when the driving shaft 2 rotates faster, thevalves 8 are seated under the action of centrifugal force, so thatcasing 4 is closed. When the speed of shaft 2 slows down to less than apredetermined value, springs 9 open valves 8 by overcoming at the sametime, the centrifugal force and oil pressure exerted upon thevalvesurface. Below said speed,

the oil amount comprised within the circumferential level indicated byline Ia and corresponding to the inner openings of the radiallyextending overflow ducts lb leading to the outlet ports 1 is expelledthrough these outlet ports and a sufiicient declutching takes placeinstantaneously. Once this declutching is effected, the volume of oilretained within casing 4 remains substantially constant, the evacuationrate of the valve being materially higher than the discharge rate ofpump 10, so that although the latter is still driven by shaft 2, the oillevel is in no way affected. Thus, as soon as the engine is speeded upagain, while valves 8 are closed under the action of centrifugal force,the clutching is effected almost instantaneously. It is to be understoodthat when the casing 4 rotates at a predetermined speed, the springforce should be sufficient to open the valves not only againstcentrifugal force but also against the oil pressure exerted upon theouter surface of valves 8.

In the embodiment shown in Fig. 3 a secondary valve I1 is provideddownstream of the primary valve 8, these two valves being interconnectedthrough passages l6 and 20; said secondary valve 11 is urged towards itsseat by a spring IS. The two valves thus open in opposite directions. Asshown in Fig. 8, the secondary valve ll may be arranged upstream of theprimary valve 8.

An additional rotary pump 2! operated from the driven shaft 3 dischargesthe liquid sucked through a pipe 22 from sump l2'into the axial duct '23and radial ducts 24 to feed the working space of the coupling in thesame manneras the above described pump I0. Bleed holes 25 located in thepump wheel 5 in the vicinity of the casing aXis and intended to evacuatethe liquid.

excess, are provided with non-return valves 26 maintained in closedposition by springs 21;. As shown in Fig. '7, these non-return valvesmay consist of balls 26 loaded by calibrated springs 21.;

This device operates as follows: As described with reference to Figs. 1and 2, when the engine is normally running, the primary valve 8 urged bya centrifugal force capable of overcoming the strength of spring!) isclosed. The secondary valve or valves I! are opened for the same reason.The casing fills up and the coupling transmits a normal torque. The. ex.cess of liquid is evacuated through bleed holes 25, since the non-returnvalves 26 are opened under the action of the discharge pressure of pumpI0. In the case when said non-return valves are constituted by balls,the objectionable action of centrifugal force liable to prevent saidballs from tightly seating is eliminated by guiding said balls in boresprovided with longitudinal grooves capable of ensuring the evacuation ofthe liquid as shown in Fig. '7.

When the engine is throttled down, the primary valve 8 opens when thespeed falls below a predetermined value due to the resulting decrease ifthe centrifugal force; the liquid is expelled out through passages 16and 20 and through the secondary valve I! which is still open, until theinner level of the liquid, due to the decrease in the centrifugal force,reaches the level indicated by line 1a. Then, the driven shaft is nolonger materially driven. If the speed further slows down, the secondaryvalves 11 close, due to the further decrease of the centrifugal forces,whereupon they remain closed until the device completely stops. Duringthis time, the device is partly filled again, but since, in themeantime, the rotation speed varies between a very low value and zero,this causes no material rotation of the driven shaft. Since the pressureof liquid within casing 4 decreases with decreasing rate of supply, thenon-return valves 26 are closed by their springs 21 to prevent theliquid from escaping through the passages 25.

Thus, in the case when the driving shaft is to be started from anexternal force applied upon the vehicle, i, e. from driven shaft 3, theamount of liquid stored in the casing may be suflicient to allow thetransmission of a torque from the driven shaft to the driving shaft evenwith a high degree of slip between said two shafts. However, in case ofcomparatively high resisting torques, the additional pump 2| operated bythe driven shaft will supply a sufllcient quantity of liquid, the valves11 remaining closed, to decrease the slip between the driving and drivenshafts and cause the engine to be started. As soon as the engine runs,the operation phases described with reference to Figs. 1 and 2, takeplace normally.

In the embodiments shown in Figs. 6 and 9, the secondary valve I1 islocated side by side with respect to the primary valve 8, so as toreduce the radial thickness of the casing'wall. The operation of thedevice is unchanged, the passage 16 interconnecting the two valvesextending circumferentially.

It will be understood that the invention is in no way limited to thetype of valves described and that the same, instead of being of theaxial type shown may be made in any other shape such as lever-controlledtilting valves. Moreover, said valves may be located in other zones ofthe easing. The above-mentioned non-return valves may be also located inany desired point, provided that they open outwardly of the casing.

What I claim is:

1. A hydraulic coupling comprising a .pump wheel rotating with a drivingshaft, a turbine wheel secured to a driven shaft, a casing fixed to saidpump wheel for rotation therewith and enclosing said turbine wheel tothereby define a work chamber, means driven by said driving shaft forcontinuously supplying liquid under pressure into said casing, a liquidoutlet port in the peripherical wall of said casing, overflow meanswithin said casing establishing a communication between said outlet portand a point of said work chamber nearer to the axis of the coupling thanthe point of said chamber remotest from said axis, an inwardly openingcheck valv arranged to cooperate with said outlet port to close the sameby centrifugal force when said casing rotates above a predeterminedspeed, and resilient means adapted to maintain said valve in openingposition as long as said casing has not attained said predeterminedrotational speed.

2. A hydraulic coupling comprising a pump wheel rotating with a drivingshaft, a turbine wheel secured to a driven shaft, a casing fixed to saidpump wheel for rotation therewith and enclosing said turbine wheel tothereby define a work chamber, a rotary pump driven by said drivingshaft for continuously supplying liquid under pressure into said casing,at least one radial liquid outlet duct within said casing and extendingfrom the peripherical wall thereof to a point of said work chambernearer to the axis of the coupling than the point of said chamberremotest from said axis, and a centrifugally operated springloaded valvemounted in said duct to close the same when said casing rotates above apredetermined rotational speed.

3. A hydraulic coupling according to claim 2, in which secondaryoutwardly opening valve means are disposed in series with saidcentrifugally operated or primary valve means, said secondary valvemeans being urged by spring means towards the closing position and bycentrifugal force towards the opening position, said spring means beingso calibrated as to bring said secondary valve means into the closingposition at a rotational speed lower than the opening or closing speedsof said primary valve means.

References Cited in the file of this patent UNITED STATES PATENTS

